The need for high quality rubber products has long been appreciated by those working in industry. This need is particularly apparent in the oil and gas industry, where numerous types of rubber products are utilized in drilling operations and in producing liquid and gaseous hydrocarbons from subterranean wells. Commonly used rubber products include, for example, stripper rubbers, hydraulic stuffing rubbers, injector rubbers, swab cups, pipe wipers, blowout preventer rubbers, O-rings, packer rubbers, drill pipe protectors and rotors for downhole pumps and motors. Because the foregoing products are typically used downhole, they are frequently subjected to extreme temperatures and pressures, severe mechanical stresses and abrasion, and continuous attack by a wide variety of degrading, scavenger liquids and gasses, which tend to break the polymer crosslinks, thereby causing the parts to fail. Accordingly, rubber parts are needed that can perform well under repeated use in such adverse and hostile conditions. Rubber compounds intended for downhole use should therefore exhibit good mechanical properties and resistance to abrasion, heat, water, fuels, chemicals, and gases. Furthermore, they should be readily vulcanizable, and should provide good processability.
Nitrile rubbers have long been recognized for their abrasion resistance and superior mechanical properties, particularly when reinforced by carbon black or mineral fillers. Conventional nitrile rubbers are copolymers of butadiene and acrylonitrile, and are commercially available in a wide range of monomer ratios from many sources. More recently, carboxylated nitrile rubbers have been recognized as providing a tough, hard vulcanizate with a higher abrasion resistance, modulus, tensile strength and tear strength than conventional nitrile rubbers. Carboxylated nitrile rubbers are also more easily workable and flow better than nitrile rubbers at conventional molding temperatures. Problems with scorching and bin stability that were encountered early on have been overcome to a great extent by using specially developed curative masterbatches and processing aids.
However, notwithstanding the improvements that have already been made, there remains a need for reinforced polymeric compounds that are readily processable, but which exhibit physical and mechanical properties that are superior to those achieved with the commercially available elastomers. Such compounds are disclosed herein.